The present disclosure relates to image forming apparatuses including an apparatus body, in which an in-body discharge space is formed, for performing image forming processing on a sheet and a post processing device for performing post processing on the sheet.
In-body discharge type image forming apparatuses include an apparatus body in the interior of which a space (in-body discharge space) is formed so that a sheet after image formation is discharged. In an in-body discharge type image forming apparatus, a sheet try, etc. is not projected from the apparatus body. Thus, it can bring advantage of small space occupancy and high accommodation capacity. Meanwhile, a post processing device may be optionally mounted in the in-body discharge type image forming apparatus after assembling in some cases. The post processing device performs post processing on a sheet, such as punch processing and staple processing. In general, since a sheet exit port opens toward the in-body discharge space, which is small, it is difficult to mount the post processing device inside the in-body discharge space.
Accordingly, when a post processing device is mounted after assembling, the post processing device is mounted on a side wall of the apparatus body of the image forming apparatus and a relay unit having a sheet conveyance function is mounted in the in-body discharge space. The side wall on which the post processing device is mounted is a side wall on the opposite side of a side wall where the sheet exit port is provided.
A sheet is conveyed to the post processing device from the exit port via a relay unit. The relay unit may entirely occupy the in-body discharge space. However, in many cases, the relay unit is mounted to the apparatus body so as to occupy part of the in-body discharge space and leave a lower region of the in-body discharge space. In the latter case, a branching mechanism is provided in the vicinity of a sheet reception port of the relay unit. The branching mechanism switches a sheet conveyance path between a path in which a sheet is conveyed to the relay unit (post processing device) and a path in which a sheet is discharged to an in-body discharge section.
In general, a method for swinging a guide plate arranged at a branching point of the conveyance path is employed for switching the sheet conveyance path. A simple mechanism to drive to make the guide plate swing is a drive mechanism which utilizes a solenoid. However, in this drive mechanism, delay time must be taken into account in operation of a movable piece of the solenoid. Further, a member for reducing operation noise and a member for mounting a peripheral mechanism are needed, which may increase the cost.
An image forming apparatus employs a mechanism using a stepping motor as a drive mechanism to swing a guide plate. With this drive mechanism, the operation delay can be prevented, and a posture of the guide plate can be controlled with high precision.